1. Field of the Invention
The present invention relates generally to the field of optics and optoelectronics, and more specifically relates to the generation of a parallel beam pattern and the reformation, correction, modulation, focusing, scanning and redirection of individual beams within the parallel beam pattern, the whole parallel beam pattern itself, and spatial positioning of the individual beams within the parallel beam pattern.
2. Discussion of the Background
As is well known, a laser emits a single focused (coherent) beam of light. A single beam laser has a wide variety of applications including medical surgery, drilling holes in materials, cutting materials, fiber optic transmission in telecommunications, free space transmission, weaponry, music recording (CDs), and of course computer data storage. Solid state laser sources have also recently become commercially available which are structured within a linear or matrix array and which emit multiple parallel beams. The light emission from individual diodes within the linear or matrix array are controlled by independent electrical signal sources.
A laser light beam, although intrinsically narrow and sharply focused, at times requires various alterations to conform to the demands of its application. Examples of a beam's alteration include expansion/contraction, refocusing, de-astigmatization, and collimation. These alterations are typically affected by various types of individual optical lenses and/or combined lens assemblies.
Further, it would be highly desirable to simply and economically redirect a laser beam, similar to the manipulation of an electron beam in a CRT. Techniques, however, which simplistically manipulate the electromagnetic field of a laser beam, and consequently redirect it, are unavailable or economically unrealistic. As a consequence, light ray redirection has historically been accomplished almost exclusively by the use of stationary or servo positioned mirrors.
A simply and economically re-directable and modulatable laser beam may find multiple applications. Examples of these types of laser beams in both a single and multiple beam pattern include:
a. Replacement display tubes for Cathode Ray Tubes (CRTs) in which screen images are directly generated; PA1 b. Biological cell targeting for laser destruction; PA1 c. Optical inspection of physical patterns; PA1 d. Direct digital (modulated) transmission; PA1 e. Selective pattern exposure on light sensitive gels; PA1 f. Parallel storage and retrieval of digital data (e.g., on stationary and dynamic media);
Within the optical data storage industry, altered laser beams are utilized in the storage and retrieval of encoded data. Such data is encoded by modifying a property of the optical storage material with a light from a laser or with heat from a focused laser beam. In either event, a laser beam emitted from the laser is precisely contracted, shaped, and focused by a series of lenses. The typical background commercial optical drive utilizes a single beam laser to read data from an optical storage media. In addition, a typical background device may use one or more lasers for writing data or for servo-tracking purposes.
Throughout developments in the optical data storage industry, researchers have attempted to develop storage systems which would utilize multiple read/write heads, acting simultaneously, in an effort to increase the transfer rate of data either written to or read from an optical storage media. One of the multi-head optical drive developers within the industry, the Asaca Corporation, announced in 1993 a magneto optic (MO) disk drive which utilizes parallel laser beams to simultaneously read/write information.
Research is being conducted into a further advance of this concept/objective via the use of solid state laser array matrices coupled with spatial light modulators. VCSELs (Vertical Cavity Surface Emitting Laser Diodes) and their equivalents which emit multiple parallel laser beams which may be used to store and recover data are one of the focal points of this research. Multiple types and varieties of lensing schemes and masks are being developed in concert with these VCSELs to manipulate, control, and redirect the laser beams emitted from these VCSELs.
With the advent of VCSELs and similar types of multiple laser beam producing arrays, the need for lensing schemes which are capable of altering and/or redirecting the multiple laser beams produced by these arrays has grown. A common requirement of these new generation of lensing schemes is that they must be able to perform their function simultaneously on the whole laser beam pattern or alternatively on individual laser beams within the whole laser beam pattern. One technique developed by Urshan Research Corporation of Los Angeles, as disclosed in U.S. Pat. No. 5,293,032, utilizes an electrically driven set of crystals to deflect a laser beam in a predetermined sequential movement.
The laser beams within the whole laser beam pattern are set on a submicro dimensional scale which is optionally less at the target than the solid state laser beam source separations. Both machinations must be performed at equivalent semiconductor switching speeds.
Another common application element of laser lensing systems within optical data storage devices is the use of rotating disk media. Systems with rotating media obviously provide at least one degree of movement of the media past a head, and coupled with servo systems of the device can further provide second and third degrees of movement, to yield a limited three dimensional freedom/excursion. Various spatial positioning systems, such as machining operations, photography, etc., likewise provide equivalent targeting schemes in which the reactive elements of the system are manipulated into a target range of the laser beam pattern rather than manipulating the laser beam pattern so as to bear on the target.